This invention relates to multi-throw switches, and more particularly to multi-throw switches that are operated by movement of a single control arm. Multi-throw switches include, for example, a single-pole-quadra-throw switch and a quadra-pole-quadra-throw switch. Basically, the former may be represented schematically by four separate momentary contact switches; while the latter may be represented schematically by four separate pairs of momentary contact switches. Preferably, these separate switches or switch pairs are somehow selectively opened and closed in response to movement of a single control arm.
Such multi-throw switches have a wide variety of applications. For example, they may be used to control the position of a TV camera or the mechanical arm of a robot. Basically, this is achieved by use of a DC motor in conjunction with the multi-throw switch wherein the polarity of the control voltage across the motor is determined by the state of the switch. That is, the control voltage across the motor may be made either positive, negative, or zero in response to the switch positions; and the motor will turn in one direction, or the opposite direction, or stop respectively in response to these voltages.
In the prior art however, a difficult problem existed because there was no inexpensive simple mechanism for manually controlling the various switch throw positions with a single control arm. As an alternative a single-pole-quadra-throw switch could be implemented by four momentary contact switches each of which have a separate push button to control its state. This configuration would be simple and inexpensive to implement, but functionally it would be clumsy at best. The four push buttons per switch simply take up too much physical space. Further, a single control arm control for a multi-throw switch is desirable because it allows for ease of coordination between the switch operator and the device being controlled. It is easier, for example, to control the flight of an airplane by moving a single control arm either forward, backward, left, or right than to fly the plane by pushing four individual push buttons.
The problem of providing a simple inexpensive linkage between one control arm and the various switch contacts is further complicated when the multi-throw switch is to be used in an explosive environment. There, the linkage mechanism must not prevent the contacts from being insulated such that contact flashings is not a problem. Similarly, if the switch is to be used in a highly corrosive environment, the linkage mechanism must not prevent the contacts from being enclosed.
Therefore, it is one object of the invention to provide an improved multi-throw switch having a single control arm.
Another object of the invention is to provide a multi-throw switch that is comprised of a plurality of reed switches wherein selective ones of the reed switches are closed by moving a magnet on the end of a control arm in close proximity to the selected reed switches.
Another object of the invention is to provide an improved single level arm control mechanism for a multi-throw switch that also has multi-poles.
Still another object of the invention is to provide an improved multi-throw switch that is operable in explosive and corrosive environments.